Structure of internal combustion engines

ABSTRACT

This internal combustion piston engine structure comprising assembled cast elements, namely a cylinder block, a cylinder head, a valve gear case and an oil sump pan, is characterised by the stacking of these elements in planes parallel to the cylinder head gasket, each element receiving separately in the form of pre-assembled sub-assemblies the mechanical components inherent thereto, the stacking of said sub-assemblies being maintained by a series of common studs screwed in the cylinder block and extending in rough-cast holes through the other assembled elements.

United States Patent 1 1 Castarede 1 STRUCTURE OF INTERNAL COMBUSTION ENGINES [75] Inventor: Armand Castarede, Billancourt,

. France 3 [73] Assignees: Regie Nationale des Usines Renault,

Paris; Automobiles Peugeot, Billancourt, both of France 22 P116111, A r.30,1973

121' Appl. No.2 355,422

[111 3,895,868 1 July-22, 1975 8/1961 Caris .l 123/195 R 2,996,050 3,046,953 7/1962 D0128 123/195 R 3,352,293 11/19 7 HUlICn 123/195 R FOREIGN PATENTS OR APPLICATIONS,

660,682 6/1938 Germany 123/195 R Primary Examiner-Wendell E. Burns Attorney, Agent, or FirmStevens, Davis, Miller & Mosher [57] ABSTRACT This internal combustion piston engine structure comprising assembled cast elements, namely a cylinder block, a cylinder head, a valve gear case and an oil sump pan, is characterised by the stacking of these elements in planes parallel to the cylinder head gasket, each element receiving separately in the form of preassembled sub as'semblies the mechanical components inherent thereto, the stacking of said sub-assemblies being maintained by a series of common studs screwed in the cylinder block and extending in rough-cast holes through the other assembled elements.

12 Claims, 8 Drawing Figures PATENTED JUL 2 2 1975 SHEET SHEET STRUCTURE OF INTERNAL COMBUSTION ENGINES nent elements such as the cylinder block and the cylin-' der head.

These elements consist as a rule of castings and up to now manufacturers endeavoured to take the maximum advantage from the possibilities afforded by this particular technique as far as the permissible shapes were concerned, with a view to construct these structure elements by minimizing the number of parts, since onepiece cylinder block and head castings have already been proposed in the art.

Although this technique is attended by a reduction in the cost of labour required for assembling operations and in the number of parts implemented, an obvious counterpart is a greater difficulty in obtaining the castings, due to their more elaborate shapes leading to an increased cost and involving machining operations requiring particularly skilled hands, so that the time gained by eliminating certain assembling steps is mostly lost due to the longer total machining time periods. Thus, the added cost resulting from this specific technique is frequently in excess of the savings made on the other hand.

By following an opposite line of thought it has also been endeavoured to make engine structures according to the so-called construction units technique wherein the major component elements are divided.

into an assembly of simpler parts. This technique, particularly employed in the construction of large engines, reduces the cost of castings which may thus be simplified considerably but increases the machining operations necessary for assembling these castings. In addi tion, the rigidity of the completely assembled engine is not so good as that of a unitary structure and therefore the assembling means must be reinforced accordingly, this increasing the final cost. Also in this case the advantages proved to be scarcely positive and under these conditions the technique of in-line piston engines underwent a kind of stabilization (as far as medium-sized engines such as automotive vehicle engines are concerned) based on the well-known conventional solution of the one-piece cylinder block with its cylinder head and valve gear cover, closed at its bottom by an oil sump or crankcase receiving the lubrication oil.

It is the essential object of the present invention to provide an engine structure of the so-called stacked construction-unit type which is free of the inconveniences set forth hereinabove and, in contrast to hitherto known propositions in this field, leads to a reduction in machining and assembling costs, in addition to the well-known advantage of reducing foundary costs.

This invention is characterised primarily by the stacking of castings in planes parallel to the plane of the cylinder head gasket, each casting receiving separately as a pre-assernbled sub-assembly the mechanical component elements inherent thereto, the stacking formed by these sub-assemblies being assembled by a series of ordinary studs screwed in the base element and extending through rough-cast holes formed in the other assembled elements. With this specific arrangement the engine structure is decomposed into a series of relatively flat component elements that can easily be manufactured under very simplified and convenient conditions throughmass-production casting methods, such as pressure or die casting or the so-called low-pressure casting technique, in the case of light alloys.

Thus, according to this invention, the cylinder head is sub-divided into two elements having flat parallel surfaces parallel tothe cylinder head gasket, one element, in the form of a casting obtained by the so-called lowpressure method, comprising the combustion chambers, the cooling circuit being obtained by means of a single sand core, said one element being pre-assembled with the valvescomplete with their seats, springs and cotter means, the other element, in the form of a case cast under pressure die-casting being adapted to receive the valve control gears. Rough-cast holes extend through these two elements in proper alignment for receiving the shanks of assembling or head studs screwed in the cylinder block. Similarly, this cylinder block will be decomposed into two elements having flat surfaces parallel to the cylinder-head gasket, one element constituting the upper portion of the block and the other the crankcase supporting the crankshaft bearings and receiving the assembling studs screwed in the cylinder block.

Advantageously, these studs are provided with a screw-threaded central or intermediate portion extending on one side towards the cylinder head and on the other side towards the crankcase. The advantage deriving from this particular arrangement is that a proper balance between the tractive efforts exerted on the screw-threaded portions of the central portion is achieved, thus eliminating considerable strain on the light-alloy internal threads of the cylinder block.

The machining of the additional joint surfaces which is required with the particular arrangement of this invention in fact, they consist in simple flat surfacing operations are advantageous in that they remove at the same time any burrs, beads and fins from the castings. These castings, having particularly open configurations, are easily produced by chill or die-pressure casting, in moulds that can be stripped directly, with uniform thicknesses.

Thus, the porosities occurring inevitably as a consequence of variable thicknesses and masses may be reduced considerably, and the hitherto necessary impregnation operation may be dispensed with.

This substantial saving obtained with the castings proper is further increased by the possibility of separately and simultaneously machining and preasembling these elements, thus reducing the time necessary for the total manufacturing cycle, these operations being facilitated by the considerably simpler design of the castins. Due to the common stud mounting, the final assembling operation is of the same order as the conventional assembling of cylinder heads on cylinder blocks. This sub-division of the component shapes, of the machining operations and of the assembling steps permits of, devising a fully mechanized manufacture.

Advantageously, rough-cast lubrication circuits may be provided in the joint planes thus created. With this arrangement, a considerably simplified pressure lubrication of adjacent rotating members, such as camshaft bearings, crankshaft bearings and any intermediate shafts, as well as the rocker shafts, may be achieved.

The rough-cast holes for the assembling studs may also a be used as oil passages leading to, or in close vicinity of, the points to be lubricated, a few outlet orifices being drilled if necessary. Also from this point of view, this inventon providesa substantial simplification in the construction and machining of internal combustion engines.

A modified form of embodiment of this invention is contemplated for avoiding the inconveniences deriving from the use of same distances between certres for the studs assembling the upper sections such as the cylinder block and the cylinder head, and those assembling the lower sections, such as the crankshaft bearing caps. thus limiting the liberty of design of the engine structure. With this modified form of embodiment it is also possible to eliminate any tapping in the light alloy element without'inasmuch utilizing tapped inserts of ferrous metal embedded in the light-alloy castings, an obviously more complicated solution.

This modified form of embodiment is characterised in that the crankcase is completed by bearing caps of ferrous metal constituting inserts formed with tapped assembling holes, aligned or not, engageable by the studs provided for assembling the caps and the bearing supports, and those of the cylinder head and cylinder block. The lower half-bearings are an integral part of the crankshaft bearing support, and the bearing cap insert constitutes the upper half-bearing fitting in a corresponding cavity of the bearing support, between this support and the lower assembling surface of the cylinder block.

As in the first form of embodiment, the abovementioned modified form of embodiment permits of assembling the engine by using separate sub-assemblies prepared beforehand. Thus, the crankshaft and its connecting-rods can be mounted to the bearing support before assembling this support with the cylinder block.

Typical forms of embodiment of the engine structure according to this invention will now be described by way of example with reference to the accompanying drawings, in which FIG. 1 is a cross-section illustrating the upper portion of an internal-combustion piston engine comprising the cylinder head and the valve-gear case, at the level of an exhaust port FIG. 2 illustrates another cross-section of the upper portion of the engine, which comprises the cylinder head and the valve-gear case, at the level of an induction port, showing in off-set section the rough-cast hole for receiving a fastening stud;

FIG. 3 is a section taken at the level of the fastening studs, showing the cylinder block and crankcase elements;

FIG. 4 illustrates in cross-section a modified form of embodiment of the invention;

FIGS. 5 and 7 illustrate in section taken along the lines VV and VII-VII of FIG. 4, respectively, a typical form of embodiment of an U-sectioned upper bearing cap in the case of an engine comprising cylinder liners; and

FIGS. 6 and 8 illustrate another form of embodiment, under the same conditions, of the T-sectioned upper bearing cap in the case of an engine without cylinder liners.

Referring first to FIG. 1, the upper elements of the engine structure according to this invention comprise a cylinder head 1 and a valve gear case 2 assembled in the plane of a joint 3 parallel to the plane of the cylinder head gasket 4; these elements are mounted on top of a cylinder block 5 (not shown), and the upper element 2 is covered by a valve gear cover 6.

The cylinder head 1 comprises a combustion chamber 7, the spark plug cavity 8, and an exhaust port.9 controlled by a valve 10; Other cavities 11 are connected to the cooling circuit of the engine block and cavities 12 correspond'to the cylinder head cooling jacket, obtained by using of a single foundry core. The

upper cavities 13 constitute the lower points of the oil flow of the timing or valve gear casev 2 and are closed thereby. Another central cavity 14 also formed in the upper joint plane is closed by the case 2 and constitutes one portion of the oil distribution passage of the pressure or forced feed lubrication system.

A drain groove 15 is also rough-cast on the element 2 adjacent the outer edge of the bearing surface 3- thereof, for sealing the assembly against oil leaks. Also mounted on the case 2 are rockers carried by a set of rocket shafts 17 and actuated by a central over-head camshaft 18. Holes 19 and 20 are provided for lubricating the camshaft bearings and the rocker shafts 17, respectively. In this last instance, the holes 20 are so drilled as to open into the rough-cast holes receiving the assembling studs 22 and also utilized as oil passages.

FIG. 2 illustrates the same component elements but seen in the plane of an inlet port 21, the inlet valve being shown at 10 1 FIG. 3 illustrates in cross-section'elements constitut ing the lower portion of the engine structure comprising the cylinder block 5 connected to the cylinder head 1 of FIGS. 1 and 2 with the interposition of a cylinder head gasket 4. This block 5 is assembled through a joint plane 23 to a bearing supporting case 24 of crankshaft 25 and of the oil pump driving shaft located in this joint plane 23. This joint plane 23 between crankcase 24 and cylinder block 5 permits of properly positioning the secondary shaft system for driving various engine members, these shafts being thus easily mounted between the two castings obtained by the pressure-casting method. As in the preceding elements the joint plane 23 has formed therein the cooling circuits 11, the lubrication oil delivery passages 14 communicating through the stud holes 22 and feed holes 20 which, in the case of bearings 24 and 26, may be rough-cast due to their presence in the crankcase joint planes 23 and 28.

In the lower joint plane 28 the crankshaft bearing caps 27 are adapted to be assembled by means of the same studs as those engaged in the holes 22 together with the lower oil sump 29 fastened to the same face 28 by means of a plurality of peripheral studs 30 clamping at the same time the elements 5 and 24 of the structure against the joint plane 23. These relatively numerous tightening points distributed centrally (studs 22) and peripherally (studs 30) ensure a rigid assembling of the relatively thin crankcase 24 with the cylinder block 5, against the lower face .23 thereof, as well as the mounting against face 28 of the separate elements 27 and 29.

The studs 22 are provided with a screw-threaded cen-.

tral or intermediate portion 31, obtained for example according to the so-called rolling method and adapted to engage corresponding tapped portions of block 5 formed in a relatively strong or reinforced portion of this block in order to ensure a better stress distribution. As the tightening stresses exerted at the ends compensate each other, these tapped portions will undergo only relatively reduced efforts so that they can safely be crank-case, with respect to the surfaces of relatively more rigid elements, such as the cylinder block, due to a proper distribution of the tightening pressures which are transmitted by the entire surface of the opposed stacked members, such as the valve-gear case, the oil sump and the bearing caps.

Referring to FIG. 4, a modified form of embodiment of the bearing support 32 constituting the lower portion of crankcase 5, of the cylinder block is shown, this support having formed therein the lower half-bearings 27, of crankshaft 25 and containing in suitable cavities 33 the cast-iron bearing caps 24 forming inserts therein. The support 32 constitutes a distortion free structure due to its considerable height and improved mouldability, thus affording a more convenient and reliable design.

The cylinder block element 5 and the lower bearing support 32 are assembled by means of studs 34 screwed in tapped holes formed in the upper U-shaped bearings 24,, for example of cast-iron, of crankshaft 25. This assembly is completed by screws 35 ensuring the necessary tightness between the two crankcase elements 5 and 32 at their joint plane 23. These screws 35 assist in stiffening the cases while relieving somewhat the stress supporting screws 34; they react against a flange 36 of the cylinder block 5 and extend through the latter before engaging tapped holes 37 formed in a projecting marginal or outer peripheral flange 38 of bearing case 32.

The light alloy structure is no more stressed through these screws 32. Thus, the single restrictive inconvenience of die-cast light-alloy crankcases is removed definitely.

By varying the position of the lower joint plane 39, any desired oil sump or mechanism can be fitted thereto, thus permitting of operating the engine under different conditions, as will readily appear to those skilled in the art.

The upper portion or element 5 constituting the cylinder block may also be of evolutive character as a function of the selected engine bore and stroke.

It may incorporate cylinder liners 40 bearing on an edge 41 of case 5, see FIGS. 5 and 7), or cylinder barrels 42 cast integrally with the case (see FIGS. 6 and 8), wherein the use of high-silica light alloys is limited only to this portion of the cylinder block 5 thus minimizing the machining operations as far as these alloys are concerned. I

Also in this case the cylinders 43 are finished by honing, this operation requiring the possibility for the tool to emerge freely through the bore.

This honing of cylinder barrels 42 may be accomplished irrespective of the interference between these barrels and the bearings 24, of crankshaft 25, since these bearings constitute inserts.

It is also possible, with this particular arrangement of the insert-forming upper bearings 24 to cast the upper portion of the cylinder block (forming the combustion chamber and the cylinder head) integrally with the crankcase 5,, whether a die-casting or an ordinary casting method is adopted therefor. A simple cap incorporating the valve gear mechanism would close the water jacket in this case.

' such as the cylinder head or the bearing supporting or Thus, the cylinder block of die-cast light alloy according to this invention will combine the advantages of an easier foundry work with those of simplified machining and assembling operations, due to the division of these operations into simpler, faster steps.

This structure is attended by a considerbly improved felxibility in actual use for the component elements of the assembly (comprising the bearing support case and the cylinder block element) can be obtained in various versions by simply using different mould impressions. the fundamental machining operations remaining unchanged, so that an engine can be personalized at a lower cost according to its particular purpose and service requirements (position, cubic capacity, etc.).

Although specific forms of embodiment of this invention have been described hereinabove and illustrated in the accompanying drawings, it will readily occur to those skilled in the art that various modifications and changes may be brought thereto without departing from the scope of the invention as set forth in the appended claims.

What is claimed as new is:

1. Internal combustion piston engine structure comprising assembled cast elements, namely a cylinder block, a cylinder head, a valve-gear case and an oil return sump, characterised in that said elements are stacked in planes parallel to the cylinder head gasket, each element receiving separately in the form of preassembled sub-assemblies the mechanical components inherent thereto, the stacking of said sub-assemblies being held by a series of common studs having an intermediate screw-thraded portion engaging corresponding tapped holes of the cylinder block, said studs extending through rough-cast holes formed in the other elements of the assembly.

2. Engine structure according to claim 1, characterised in that the cylinder head consists of light alloy cast according to the so-called low-pressure technique, the other elements consisting of light alloy cast according to the die-casting method.

3. Engine structure according to claim 1, characterised in that the lubrication circuits are rough cast in the assembling or joint planes of the stacked elements.

4. Engine structure according to claim 3, characterised in that the rough-cast holes engaged by the assembling studs are connected to the lubrication circuits for directing the oil to points adjacent to the various members to be lubricated.

5. Engine structure according to claim 1, characterised in that one of the stacked elements is a crankshaft bearing supporting case mounted to the lower portion of the cylinder block and receiving in its lower assembling plane, independently, the crankshaft bearing caps and the lower oil sump pan.

6. Engine structure according to claim 5, characterised in that said bearing support case is fastened to the cylinder block on the one hand by central fastening ing support case and of the cylinder block.

7. Engine structure according to claim 2, characterised in that said assembling studs are screwed in the cylinder block by means of an intermediate screwthreaded portion formed on each stud, the latter extending on either side of said portion with plain portions passing through the elements to be assembled which are held ,and tightened in position at either end of said studs.

8. Engine structure according to claim 1, characterised in that one of the stacked elements is a case supporting .the crankshaft bearings, completed by bearing cap inserts of ferrous alloy comprising tapped assembling holes, aligned or not, engageable by the assembling studs of the bearing caps and bearing supports, and by those of said cylinder head and said cylinder block.

9. Engine structure according to claim 8, characterised in that the lower half-bearings are an integral part of the crankshaft bearings, adequate cavities being formed in said support to permit the mounting of the bearing caps constituting the upper half-bearings between the bearing support and the lower assembling face of the cylinder block element.

10. Engine structure according to claim 9, characterised in that the tapped holes of the bearing caps are adapted to be engaged at their upper and lower ends by the relevant ends of the studs for fastening the crankshaft bearing support and by the studs provided for fastening the cylinder block and cylinder head, respectively.

11. Engine structure terised in that said bearing support fastening studs, on the one hand, and said cylinder block and cylinder head fastening studs, on the other hand, consist of a single rod formed with an intermediate screw-threaded portion engaging the corresponding bearing caps.

12. Internal combustion piston engine structure comprising assembled cast elements including:

a cylinder block cast integrally with a cylinder head;

' a valve gear case; a case supporting the crankshaft bearings; and,

an oil return sump characterised in that said elements are stacked in mutually parallel planes, each element receiving separately in the form of pre -assembled sub-assemblies the mechanical components inherent thereto the stacking of said sub-assemblies being held by a series of common studs having an intermediate screw threaded portion engaging corresponding tapped holes of the cylinder block-head assembly, said studs extending through rough-cast holes in other elements of the assembly, said shaft bearings, adequate cavities being formed in saidsupport to permit the mounting of bearing caps constituting upper half bearings between the bearing support and the lower assembling face of the cylinder block element.

according to claim 10, charac- 

1. Internal combustion piston engine structure comprising assembled cast elements, namely a cylinder block, a cylinder head, a valve-gear case and an oil return sump, characterised iN that said elements are stacked in planes parallel to the cylinder head gasket, each element receiving separately in the form of pre-assembled sub-assemblies the mechanical components inherent thereto, the stacking of said sub-assemblies being held by a series of common studs having an intermediate screw-thraded portion engaging corresponding tapped holes of the cylinder block, said studs extending through rough-cast holes formed in the other elements of the assembly.
 2. Engine structure according to claim 1, characterised in that the cylinder head consists of light alloy cast according to the so-called low-pressure technique, the other elements consisting of light alloy cast according to the die-casting method.
 3. Engine structure according to claim 1, characterised in that the lubrication circuits are rough cast in the assembling or joint planes of the stacked elements.
 4. Engine structure according to claim 3, characterised in that the rough-cast holes engaged by the assembling studs are connected to the lubrication circuits for directing the oil to points adjacent to the various members to be lubricated.
 5. Engine structure according to claim 1, characterised in that one of the stacked elements is a crankshaft bearing supporting case mounted to the lower portion of the cylinder block and receiving in its lower assembling plane, independently, the crankshaft bearing caps and the lower oil sump pan.
 6. Engine structure according to claim 5, characterised in that said bearing support case is fastened to the cylinder block on the one hand by central fastening studs extending through the complete stacked elements from the valve gear case to the crankshaft bearing caps and on the other hand by outer peripheral studs permitting the stacking of the lower oil sump pan, of the bearing support case and of the cylinder block.
 7. Engine structure according to claim 2, characterised in that said assembling studs are screwed in the cylinder block by means of an intermediate screw-threaded portion formed on each stud, the latter extending on either side of said portion with plain portions passing through the elements to be assembled which are held and tightened in position at either end of said studs.
 8. Engine structure according to claim 1, characterised in that one of the stacked elements is a case supporting the crankshaft bearings, completed by bearing cap inserts of ferrous alloy comprising tapped assembling holes, aligned or not, engageable by the assembling studs of the bearing caps and bearing supports, and by those of said cylinder head and said cylinder block.
 9. Engine structure according to claim 8, characterised in that the lower half-bearings are an integral part of the crankshaft bearings, adequate cavities being formed in said support to permit the mounting of the bearing caps constituting the upper half-bearings between the bearing support and the lower assembling face of the cylinder block element.
 10. Engine structure according to claim 9, characterised in that the tapped holes of the bearing caps are adapted to be engaged at their upper and lower ends by the relevant ends of the studs for fastening the crankshaft bearing support and by the studs provided for fastening the cylinder block and cylinder head, respectively.
 11. Engine structure according to claim 10, characterised in that said bearing support fastening studs, on the one hand, and said cylinder block and cylinder head fastening studs, on the other hand, consist of a single rod formed with an intermediate screw-threaded portion engaging the corresponding bearing caps.
 12. Internal combustion piston engine structure comprising assembled cast elements including: a cylinder block cast integrally with a cylinder head; a valve gear case; a case supporting the crankshaft bearings; and, an oil return sump characterised in that said elements are stacked in mutually parallel planes, each element receiving separately in the form of pre-assembled sub-assembliEs the mechanical components inherent thereto the stacking of said sub-assemblies being held by a series of common studs having an intermediate screw threaded portion engaging corresponding tapped holes of the cylinder block-head assembly, said studs extending through rough-cast holes in other elements of the assembly, said case supporting the crankshaft bearings being completed by bearing cap inserts of ferrous alloy comprising tapped assembling holes engageable by the assembling studs of the bearing caps and bearing supports and by those of said cylinder block-head assembly, lower half bearings being an integral part of said crankshaft bearings, adequate cavities being formed in said support to permit the mounting of bearing caps constituting upper half bearings between the bearing support and the lower assembling face of the cylinder block element. 